Pretty clear cut to me, to be honest. FF XII, while being my third favourite FF (VIII, X, XII, VII, VI, as my top five), it doesn't hold a candle to the craze that began with Pokemon Red & Blue. The formula of catching em' all, training them, and battling them that started with Pokemon Red & Blue is still selling like crazy whenever a new game is released, and this is fifteen years later.
Unlike most nostalgic games in this polls, I wouldn't ever play them over their counterpart in the poll which I vote against, because I realize that time has passed a lot of these games by (I would play DR over Tetris for example), but for Pokemon Red, that game is still a fucking addictive blast to play. FF XII's combat was it's saving grace, for it's story and characters were bland - it doesn't warrant winning this.